This invention relates generally to butterfly valves. In another aspect, the invention relates to such valves having resilient liners for tight shut-off and being adapted for use with a manual or automatic actuator.
In butterfly valves designed for tight shutoff, it has been common to employ a cast-metal valve body which is provided with a resilient liner of some suitable material such as an elastomer, halocarbon polymers, and the like. Typically, the body castings of these prior art valves have been provided with a boss on the body to which is attached an automatic or manual valve actuator.
Such cast-body valves are expensive and cumbersome to manufacture, because the casting must ordinarily be inspected visually or by X-ray methods for flaws, the flaws welded, and the body machined on various surfaces with the attendant generation of substantial amounts of scrap metal shavings.